The present invention relates generally to data conversion systems, and more particularly to digital-to-analog converters.
In data conversion system, it is desirable to reduce spurious voltages and currents so that the resulting output accurately represents the input value while minimizing any error. In a digital-to-analog converter (DAC) system, a differential transistor pair is utilized to provide control of a current source in converting a digital signal input into an analog output current or voltage. Where the transistors are metal oxide semiconductor field effect transistors (MOSFETs), output glitches may be reduced by ensuring that the transistors are not turned off simultaneously. Prior systems utilized inverters in an attempted to control the crossover voltages of the differential pair. However, using inverters is disadvantageous because inverter threshold variation over the process and temperature, must be adjusted, and is difficult to predict and account for. Additionally, inverters may produce unacceptable noise due to current spikes produced during state transitions. Thus, there lies a need for, inter alia, a method and apparatus for providing improved crossover voltage control of a differential pair.